Stencil



Oct. 11, 1932. D, SMITH 1,882,526

sTENoIL Filed Deo. 25. 1950 F/GJ.

I. lf

Patented oa. 11, 1932 UNITED-STATES PATENT ol-Flca- Y CHARLES D. SMITH, OF SHARON HILL, PENNSYLVANIA, ASSIGNOR TO THE DALLET'I -COHPANY, 0F PHILADELPHIA, PENNSYLVANIA, A CQBPOBATION OF PENNSYL- 'VARIA BTENOL Application died December 23, 1930. Serial No. 504,316.

bly invention relates to .an improvement in. stencils such are used in connection with thel sand blasting of lettersl or' figures on stone, Wood,` glass, etc., etc. My invention more particularly relates to the production of a stencil which may be repeatedly used. t

Heretofore in the preparation of a stencil for use in connection with the sand blasting 0 of stone, Wood, and the like, it has been customary to cover the surface of Athe object to be sand blasted with a plastic or iuid material by means, for example, of heat, permitting the material to harden, and cutting out the letters or figure to be sand blasted. When the sand blasting is completed, the stencilmaterial is-removed, but the stencil is necessarily destroyed in the process of removal and for a repetition of the letters or ligure a new stencil must be cut. Less usually stencils have heretofore been provided comprising material laid on a paper back ing and adapted to be adhered to the surface of an object to be stenciled through the rendering of the materialadhesive to the object say, for example, by the application of heat to a surface thereof. Such stencils,

however, are subjected to destruction on removal after com letion of the sand blast.

Further-stenci "s have been provided comn prising desirable material capable of resisting sand blast and adapted to be axed to the surface to besand blasted through the medium of an adhesive, as glue. Such stencils, While they are not destroyed in removal from the surface, are undesirable since the surface to which the stencil vwas adhered must be cleaned to remove the glue and where the surface is of a delicate nature, as for example, where coated with paint, removal of the glue is substantially impossible without injury to tt e surface.

Now, it is the object of my invention to provide a stencil which may be readily adhered to thesurface of an object to be sand blasted and which on completion of the sand blasting may be readily removed from the object without injury and in a condition for reuse. The stencil in accordance with my invention may be repeatedly reused.

In accordance with my invention provide a stencil comprising laminated sheets,v

one of which is composed of a material capable of being rendered suiiiciently adhesive to a surface to be mnd blasted as to maintain the stencil in place during the sand blastin and, at the same time, having insuiiicient a hesion to cause it, or the surface to which it is applied, injury on removal, and of such a character as to leave the surface to which it is applied without the deposit of any adhesive. The shell of thev laminated sheets is composed of a material of such a charac-l ter as to enable the first described sheet to adhere to it and, at the same time, of ,such a character as to resist the action of the sand blast. The sheet adapted to adhere to the surface to be sand blasted may be relatively thin compared to the thickness of the sheet ada ted to resist the action of the sand blast.

llhving indicated in a general way the nature and purpose of my invention, I will proceed to a detailed description thereof with particular reference to the accompanying drawing, in which:

Figure 1 is a sectional view showing a surface to be sand blasted with a stencil embodying my invention associated therewith.

Figure 2, is a perspective view of the subject matter of Flgure 1.

Fig. 3 is a sectional shown onA a vlarger scale. e

In the drawing a indicates asurface to be sand blasted, as for example, the surface of View of the stencil a piece of stone, wood, glass or the like. b

indicates a sheet of material having the capacity for resisting the action of a sand blast,

superimposed upon a relatively thinner sheet of material c, to which it isv adhered and which in turn is capable of bein rendered adherent to thesurface a. d, d in 'cates letters cut through the superimposed sheets b and c and which are adapted to be sand blasted into the surface a. v

By way of example, the sheet b may be formed by a formaldehyde condensation product or synthetic rubber formed, for example, by dgesting a mixture of about 25 pounds of glue, 12 pounds of golcerin and 12 pounds of water for a peri of about twenty-four hours, .then cooking at a temperature of about 80 C. for about four hours and finally adding formaldehyde for the production of a water-insoluble condensation product. The material so produced is sheeted in any suitablemanner, as for example, by casting or by flowing the material on a surface, for the formation of a sheet of desired thickness.

By way of example, the sheet c, capable of being rendered adherent to a surface to be sand blasted, and desirably softer than the sheet b, may be cast directly on the sheet b, a sheet of light weight blotting paper e being interposed between the sheets. The sheet c, for example,'may be formed by castin on the sheet ba composition composed o about 25 pounds of glue, 6 pounds of glycerin and 14 pounds of water. When the sheet c has hardened, the exposed surface thereof will desirably be dusted over withl talcum powder. It will be noted that the sheetv c when cast on the sheet b will adhere thereto and form a unitary structure. Where a sheet of light weight blotting paper is interposed between the sheets, the blotting pa per will become saturated with the compo-` sition forming the sheet c when it is cast and adherence between the sheets will be permitted, since the compositiondmpregnated fibres of` the surface of the blotting paper lying against the surface of the sheet f Will tenaci'ously adhere to sheet f.

lVhen it is desired to use the stencil fornied exposed surface of the sheet c to render it sufficiently adhesive to retain the stencil in place after the`wetted surface has been pressed upon the surface to be sand blasted.V When the stencil is adhered to the surface to. Vbe sand blasted, or previously if desired, the

letters or figures to be sand blasted are cut out. Since the material of sheetb is strongly resistant to the action of the sand blast, the

stencil will be found to be little injured by the sand blast and may be readily stripped off, since the adherence of sheet c to the surface, while sufiicient to maintain the stencil in place, is not such as to cause thev stencil to be injured in its removal. Further, the adherence of the sheet c to the surface is not such as to leave any of the composition of which the sheet is formed on the surface. In

other words, the stencil on removal will leave the surface clean.

The stencil in accordance with my invensylvania, on this sired letters or figures, since it may be readily and cleanly cut, the softer sheet c being supp kadherent to form a unitary struct-ure with sheet b and to maintain the stencil inl place and, at the same time, insufficiently adherent to cause injury to the stencil or to a surface on its removal.

Vhat Ij claim and desire to protect by Letters Patent is 1. A stencil material for abrasive blasting ,comprising a laminated sheet including an upper sheet composed of abrasive resistant material, a lower sheet adhered to the upper sheet and composed of a material capable of being rendered tacky by the application of water and an intermediate sheet adhered to both the upper and lower sheets.

2. A stencil material for abrasive blasting comprising a laminated sheet including an upper sheet composed of synthetic rubber b-an'da' lower sheet composed of amixture of glue and glycerine.

3. A stencil material for abrasive blasting comprising a laminated sheet including an upper sheet composed of synthetic rubber. a

lower sheet composed of a mixture of glue and glycerine and an intermediate sheet coinposed of blotting paper.

v In testimony of which invention,v I have hereunto set my hand, at Philadelphia, Penu- 19tl1 day of December. 1930. CHARLESl D. SMITH.

tion may be adhered with equal readiness and efficiency to surfaces of various kinds, as wood, glass, metal, etc., etc. and may be as readily cleanly removed therefrom and may be safely applied to painted surfaces, since the adherence of sheet c will not be such as to injure a painted surface on removal. Further, the stencil in accordance with my invention lends itself to the formation of any de- 

